Calculate the molar mass of molecular iodine, I2: 79.9 g/mol Only atomic masses, and not molar masses, can be calculated for elements. 159.8 g/mol 126.9 g/mol 253.8 g/mol
The Correct Answer and Explanation is:
The molar mass of molecular iodine (I₂) is calculated by adding the molar masses of two iodine (I) atoms.
The atomic mass of iodine (I) is approximately 126.9 g/mol. Since iodine exists as a diatomic molecule (I₂) in its natural form, we need to multiply the atomic mass of iodine by 2 to find the molar mass of I₂.
Molar mass of I₂ = 126.9 g/mol × 2 = 253.8 g/mol
This means that 1 mole of molecular iodine weighs 253.8 grams.
Explanation:
- Atomic mass vs. Molar mass: The atomic mass of an element is the mass of a single atom, typically measured in atomic mass units (amu or g/mol). The molar mass is the mass of one mole of molecules or atoms of a substance, expressed in grams per mole (g/mol). For elements, the atomic mass and the molar mass are numerically equal, but the molar mass applies to a collection of atoms (1 mole).
- Iodine in nature: Iodine is a halogen element and is typically found in nature as a diatomic molecule (I₂). This is why we multiply the atomic mass of iodine by 2.
- Why 253.8 g/mol? The molar mass of iodine (I) is 126.9 g/mol, and when we have two iodine atoms in I₂, we multiply this value by 2. Hence, the molar mass of I₂ is 253.8 g/mol.
Thus, the correct molar mass of molecular iodine (I₂) is 253.8 g/mol.
